The goal of the Biostatistical Core is to provide collaborative support for the design, data transfer and management, analysis and reporting of the three CISRC projects proposed in this grant. Statistical and data management support are necessary to ensure the consistency and quality of the design, conduct, analysis and reporting of scientific trials that are critical components of any collaborative scientific endeavor. With a common experimental design among the three projects, many data management and quality control issues will be shared among projects. By using the shared resource of the Biostatistical Core, all three projects proposed will benefit from the experience gained in each project. Centrally collected, processed and transferred data between the CIS offices, the CIS Central Support and the Survey Methods Core will provide integrated functions across the Core elements of the program project and will keep individual projects operationally centralized and consistent. Specifically, the Biostatistics Core will provide statistical collaboration in experimental design, sample size, computer-related questionnaire design, assistance in data collection, processing and retrieval, and analysis and interpretation of within-project and cross-project outcome data for the CISRC projects.